The O(D)-equivariant fuzzy hyperspheres

We present some new fuzzy spheres of dimensions d≥1 covariant under the full orthogonal group O(D), D=d+1. They are built by imposing a sufficiently low energy cutoff on a quantum particle in the D-dimensional real euclidean space, subject to a confining potential well V(r) having a very sharp minimum on the sphere of radius r=1; furthermore, as the cutoff and the depth of the well depend on (and diverge with) a natural number Ʌ, so do the Hilbert space and the algebra of observables, ensuring that the latter actually characterize a fuzzy space. The commutator of the coordinates depends only on the angular momentum, as in it Snyder noncommutative spaces; and as Ʌ→+∞ the Hilbert space dimension diverges, the fuzzy d-dimensional hypersphere converges to the usual d-dimensional hypersphere, so we recover ordinary quantum mechanics on it. In addition, we study the eigenvalue equation for the "cartesian coordinates" observables on the fuzzy d-dimensional hypersphere and then we construct various systems of coherent states (SCS) on the fuzzy circle (d=1) and the fuzzy sphere (d=2). These models might be useful in quantum field theory, quantum gravity or condensed matter physics